问动态创建rbl时，单选按钮列表结果不起作用

EN

Sub Page_Load(ByVal Sender as Object, ByVal E as EventArgs)

        For i As Integer = 1 To 20

            Dim TableRow As New TableRow()
            Dim TableRowCell_1 As New TableCell()
            TableRow.Cells.Add(TableRowCell_1)
            holidayQuestionnaireTable.Rows.Add(TableRow)

            Dim question As New RadioButtonList
            question.ID = "question" & i

            question.Items.Insert(0, new listitem("", "1"))
            question.Items.Insert(1, new listitem("", "2"))
            TableRowCell_1.Controls.Add(question)

        Next

End Sub

Sub btnSendFeedback_Click(sender as Object, e as EventArgs)

    Dim question1 As RadioButtonList = DirectCast(Page.FindControl("question1"), RadioButtonList)
    Dim question2 As RadioButtonList = DirectCast(Page.FindControl("question2"), RadioButtonList)
    Dim question3 ...
    ...
    Dim question19 As RadioButtonList = DirectCast(Page.FindControl("question19"), RadioButtonList)
    Dim question20 As RadioButtonList = DirectCast(Page.FindControl("question20"), RadioButtonList)

    Dim rblCount As Double
    Dim total As Double
    Dim avg As Double

    For Each ctrl As UI.Control In Me.myPanel.Controls
        If TypeOf ctrl Is RadioButtonList Then
            Dim rbl As RadioButtonList = DirectCast(ctrl, RadioButtonList)
            If rbl.SelectedIndex > -1 And not rbl.ID = "question18" Then
                Dim value As Double = Double.Parse(rbl.SelectedValue)
                total += value
                rblCount += 1
            End If
        End If
    Next

    Response.Write(rblCount & " - " & total & " - " & (total / rblCount))

End Sub

<asp:Placeholder ID="myPanel" runat="server">
        <asp:Table runat="server" CellPadding="0" CellSpacing="0" GridLines="None" HorizontalAlign="Center" CssClass="ratingtable" ID="holidayQuestionnaireTable" />
        <asp:Button OnClick="btnSendFeedback_Click" runat="server" Text="Submit..." ID="submitbutton" />
</asp:Placeholder>